1. Field of the Invention
The invention relates to a steering system.
2. Description of Related Art
In terms of a rack-and-pinion steering system, there has been proposed a dual-pinion steering system in which a main pinion for transmitting manual steering effort from a steering wheel and an auxiliary pinion for transmitting steering auxiliary force caused by an electric motor are respectively engaged with their corresponding racks of a rack shaft. Usually, a pair of end portions of the rack shaft is supported slidably in its axial direction by a rack bush held by a housing. In Japanese Utility Model Application Publication No. 64-18977, that end portion of the pair of end portions of the rack shaft which is closer to the auxiliary pinion is received by an eccentric bearing bush serving as the rack bush. The eccentric bearing bush changes a position for pivoting the rack shaft according to a rotating position thereof, thereby adjusting an engagement state between the auxiliary pinion and the rack shaft.
In the meantime, as illustrated in a schematic view of FIG. 24, two pinions 91, 92 which include helical teeth fowled substantially in the same direction and of which axial directions are substantially parallel to each other respectively mesh with racks 94, 95 formed on the substantially same side surface of a rack shaft 93. In this case, the rack shaft 93 during steering receives, from both of the pinions 91, 92, component forces of a meshing reaction force in a direction (a direction shown by a void arrow in the figure) substantially parallel to the axial directions of the pinions 91, 92, and performs a translational motion.